Postretirement Benefits (Details 9) (Employee pension plan)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Target asset allocation for the portfolio:
Total plan assets (as a percent)	100.00%	100.00%
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	100.00%	100.00%
Total equity securities
Target asset allocation for the portfolio:
Total plan assets (as a percent)	60.00%	60.00%
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	62.00%	60.00%
U.S. equity securities
Target asset allocation for the portfolio:
Total plan assets (as a percent)	40.00%	40.00%
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	41.00%	41.00%
US Small Capitalization Core Equity
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	20.00%
US Large Capitalization Core Equity
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	39.00%
Us Equity Index [Member]
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	41.00%
Non-U.S. equity security
Target asset allocation for the portfolio:
Total plan assets (as a percent)	20.00%	20.00%
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	21.00%	19.00%
International Small Capitalization Risk Controlled Equity
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	11.00%
Emerging Markets Equity
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	11.00%
International Risk Controlled Equity
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	78.00%
Debt securities - U.S. fixed income
Target asset allocation for the portfolio:
Total plan assets (as a percent)	39.00%	39.00%
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	37.00%	39.00%
Long Duration Fixed Income
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	50.00%
Long Duration Corporate Fixed Income
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	50.00%
Other
Target asset allocation for the portfolio:
Total plan assets (as a percent)	1.00%	1.00%
Actual asset allocation for the portfolio:
Total plan assets (as a percent)	1.00%	1.00%